Phylogeny, diversity, and species delimitation of the North American Round-Nosed Minnows (Teleostei: Dionda), as inferred from mitochondrial and nuclear DNA sequences

► Nuclear and mitochondrial genes support the recognition of 12 species of Dionda. ► Six described and currently recognized species of Dionda are valid species. ► We remove two species of Dionda (D. texensis and D. flavipinnis) from synonymy. ► We identify four species of Dionda that are currently undescribed. ► Many of the species of Dionda are endangered and are in need of protection.